Hair trimmer



FIG. 1 is a perspective view of a hair trimmer showing my new design in its environment;

FIG. 2 is a left side view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a front side view thereof;

FIG. 5 is a right view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines showing the trimmer blade are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a hair trimmer, as shown and described. 